# Energy 2

Discipline
Materials

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Motion (velocity) is caused and changed by acceleration, which is caused by forces, which is caused by interactions with their momentum. What, then, causes interactions? Or more accurately, what starts an interaction?

This Energy discipline will enable you to answer questions like ‘how fast will the arrow fly when releasing the crossbow spring?’.

2nd of 2 courses in the Energy discipline.
Meet the other participants in the Energy classroom.

New properties
Kinetic energy $K$
Gravitational potential energy $U_g$
Elastic potential energy $U_\text{elastic}$
Work $W$
Heat $Q$
Power $P$

New mechanisms
Kinetic energy $$K_\text{trans}=\frac 12 mv^2$$
$$K_\text{rot}=\frac 12 I\omega^2$$
Potential energy $$\vec F=-\nabla U$$
$$U_g=mgh$$
$$U_\text{elastic}=\frac12 k\Delta L^2$$
Work $$W=F\Delta s$$
Work-energy theorem $$W_\text{all}=\Delta K$$
Energy conservation law $$E_1+W+Q=E_2$$
Power $$P=\frac{\mathrm dE}{\mathrm dt}$$

New phenomena
Energy $$E$$
Equilibrium $$\sum \vec F=0$$$$\sum \vec \tau=0$$
No-energy rolling

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• 14 Skills